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Rationale: Accessory spleen torsion is a rare cause of the acute abdomen. The complications of accessory spleen torsion, such as intestinal obstruction, are rarer. We herein report a case of colonic obstruction caused by accessory spleen torsion because of the unusual condition.

Interventions: We performed emergency laparotomy and found that accessory spleen torsion pressured against splenic flexure and descending colon, and caused colon obstruction. The patient underwent accessory splenectomy and enteral decompression.

Outcomes: At 6 months follow-up, the patient recovered well with perfect digestion.

Lessons: Accessory spleen torsion and its complications are extremely rare. This entity should be considered in differential diagnosis of acute abdomen. However, in case of acute abdomen with critical clinical situation, emergency surgical intervention is necessary for timely diagnosis and treatment.

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1 Introduction

Accessory spleen is a congenital anomaly, with the incidence of approximately 10% to 30% in the population.[1,2] However, most accessory spleens are asymptomatic. Accessory spleen torsion is a rare entity causing acute abdominal pain with occasional complications such as infarction, spontaneous rupture and hemorrhagic shock, infection and peritonitis, and intestinal obstruction.[2–6] Here we report a rare case of colonic obstruction caused by accessory spleen torsion, and review the relevant literatures.

2 Case report

A written informed consent was obtained from the patient's legal guardian for publication of this case report, and the study was approved by the ethics committee of Anhui Provincial Hospital affiliated to Anhui Medical University.

A 15-year-old boy was admitted to our emergency department with a 3-day history of intense, constant pain in the left side of the abdomen, accompanied by nausea, vomiting, and a failure to pass flatus or bowel movements. His medical history was unimportant except for exercise 3 days ago. On admission the patient had moderate pyrexia (38.5°C), his blood pressure [BP] was 114/74 mm Hg, respiratory rate was 25 breaths/min and pulse was 135 beats/min. Physical examination revealed fullness in the left upper quadrant, there was tenderness to palpation of the whole abdomen, the point of the greatest tenderness with signs of peritoneal irritation in the left upper quadrant and left flank. The bowel sounds were hyperactive. Laboratory examination revealed white blood cell count of 18,400 cells/mm3 (normal values 3500–9500 cells/mm3) with 83.9% neutrophilia. The abdominal plain radiography revealed the dilation of the large bowel (Fig. 1). Abdominal ultrasonography showed an oval hypoechoic mass in the left midabdomen, about 9 × 7 × 4.5 cm, and a small amount of free peritoneal fluid. Computed tomography (CT) scan demonstrated a small amount of ascites and a well-defined, soft tissue mass in the left midabdomen, about 9 × 7 × 4 cm with edema in the surrounding fat (Fig. 2). Dilated gas-filled transverse colon was observed. The liver, spleen, kidneys, stomach, and pancreas were in normal location and without any morphological changes (Fig. 3). We made the diagnosis of peritonitis and acute mechanical intestinal obstruction secondary to intraperitoneal tumor, and performed an emergency laparotomy. On exploration, a grossly distended transverse colon with air-fluid content was found; there was a bluish, congested, soft mass anterior to colonic splenic flexure and descending colon, about 10 × 7 × 4.5 cm. The mass was attached to splenic hilum and twisted around a vascular pedicle with a 720° torsion, compressing splenic flexure and descending colon. About 200 mL of cloudy, greenish-yellow free fluid was observed in the peritoneal cavity. A spleen with normal appearance was found in the orthotopic site. There was no intestinal necrosis or other abnormalities after further abdominal examination. We made the diagnosis of colonic obstruction caused by accessory spleen torsion, and performed accessory splenectomy and enteral decompression. Hematoxylin and eosin stain of the specimen showed red pulp, white pulp, and infarcted tissue; malignant cell was not observed (Fig. 4). In addition, the mass came from splenic hilum and cut surface was similar to spleen. The diagnosis of accessory spleen infarction was made postoperatively. The patient made an uneventful recovery and was discharged 7 days after surgery. In retrospect, a pedicle originating from splenic hilum to the mass was identified on CT image (Fig. 5). At 6 months follow-up, the boy recovered well with perfect digestion.

3 Discussion

The spleen develops from mesenchymal tissue in the dorsal mesogastrium during the fifth week of fetal life. An accessory spleen may arise from incomplete fusion of these mesenchymal buds.[5,7] Because the spleen originates in the dorsal mesogastrium and then rotates to the left side of the abdomen, accessory spleens are always located in the left side of the body. The most common sites of accessory spleens are in the splenic hilum (75%) and in the pancreatic tail (20%), the remaining 5% of the sites include the gastrosplenic ligament, splenocolic and gastrocolic ligaments, splenic artery, greater omentum, mesenterium, left scrotum, and mediastinum.[2,3,7,8] Accessory spleens generally range in size from 2 to 4 cm and receive blood supply from the branches of the splenic artery; only a few cases of large accessory spleen more than 10 cm in size have been reported.[6,9,10] In our case, the patient had large accessory spleen.

Accessory spleen torsion is a rare entity, and only 31 cases (including this case) were reported in English literatures.[1–28] Torsion of an accessory spleen generally presents as nonspecific acute abdominal pain, some of which is accompanied by fever, nausea, vomiting, leukocytosis, and ascites. These clinical manifestations are related to 3 features: First, torsion of an accessory spleen will undergo infarction and strangulation, producing acute inflammation.[6,11] Second, twisting of the vascular pedicle results in venous congestion, causing enlargement and swelling of the accessory spleen.[12] Third, direct mechanical interference to adjacent organs.[3] All 3 of these features were observed in our case. Although there was no evidence of relationship between size, origin, and torsion, exercise may be a cause of accessory spleen torsion in this case.

Other complications of accessory spleen torsion are even rare, such as spontaneous rupture and hemorrhagic shock, infection and peritonitis, and intestinal obstruction. Only 1 case of intestinal obstruction caused by accessory spleen torsion was reported previously in which small bowel and colon were adherent to accessory spleen.[3] However, our case is distinct because accessory spleen torsion pressured against splenic flexure and descending colon, and caused mechanical colon obstruction. This presentation may relate to the enlargement of accessory spleen due to venous congestion and the location approaching to splenic flexure and descending colon.

Interestingly, systemic inflammatory response syndrome (SIRS) was observed in the patient, whose body temperature was 38.5°C (>38°C), heart rate was 135 beats/min (>90 beats/min), respiratory rate was 25 breaths/min (>20 breaths/min), the white blood cell count was 18,400 cells/mm3 (>12,000 cells/mm3). These clinical parameters fulfilled all 4 SIRS criteria recommended by the American College of Chest Physicians/Society of Critical Care Medicine Consensus Conference.[29] To the best of our knowledge, this is the first report of SIRS in such cases. We cannot completely explain the clinical presentation. Nonetheless, the presentation of SIRS is likely to be related to intestinal obstruction with resultant bacterial translocation (BT) [30] and accessory spleen infarction with resultant inflammatory changes. Many studies have shown that BT or gut-derived factors may provoke SIRS.[31,32]

Preoperative diagnosis of accessory spleen torsion is very difficult, even with the modern imaging tools. Abdominal CT and ultrasonography examinations are helpful to make diagnosis.[5] CT scan may disclose the mass and evaluate the shape, size, and changes of surrounding tissues, and contrast-enhanced CT may reveal a hypodense mass with peripheral enhancement.[9] However, it is impossible to make accurate diagnosis unless a twisted vascular pedicle can be found.[13] Ultrasonography findings include a well-defined, hypoechoic, and homogeneous mass.[11] Doppler ultrasonography may confirm the avascular nature, but cannot distinguish between a cystic mass and accessory spleen torsion.[14] Magnetic resonance imaging (MRI), scintigraphy and angiography can provide significant information, but they are not always available in an emergency condition.[7,15] In our case, emergency laparotomy was performed to arrest strangulated intestinal obstruction and avoid the progression to multiple organ dysfunction syndrome (MODS) from SIRS.[33] There was not enough time to perform contrast-enhanced CT, MRI, scintigraphy, and angiography.

Differential diagnosis should be considered preoperatively. A presumptive diagnosis of intraperitoneal tumor was made due to routine CT and ultrasonography revealing soft tissue mass. Enhanced CT might establish the nature of the mass but was of unknown origin. Intussusception was suspected because of abdominal mass and intestinal obstruction, but a target or sandwich sign on ultrasonography and a targetlike appearance on CT scan may confirm the diagnosis of intussusception. Abscess was another possibility, which appeared as a hypoattenuating lesion on CT scan and the presence of gas was typical CT findings.[19]

In conclusion, accessory spleen torsion and its complications, such as intestinal obstruction, are extremely rare. It is very difficult to make an accurate diagnosis preoperatively. This entity should be considered in differential diagnosis of acute abdomen. However, in case of acute abdomen with critical clinical situation, emergency surgical intervention is necessary for timely diagnosis and treatment.

[29]. American College of Chest Physicians/Society of Critical Care Medicine Consensus Conference. Definitions for sepsis and organ failure and guidelines for the use of innovative therapies in sepsis. Crit Care Med 1992;20:864–74.